libt2n - (talk to neighbor)

0.7

Introduction

libt2n (talk to neighbor) is a C++ library for inter-process communication (IPC [1]) with an additional code generator (libt2n-codegen) to make C++ remote procedure calls (RPC [2]) simple.

Using libt2n and its code generator only the server procedure implementations have to be written manually. The stubs are generated by the code generator and the inter-process communication routines are provided by libt2n. libt2n provides an abstract interface for connections hiding the details of the concrete communication mechanism used. At the moment it is implemented for local sockets (a.k.a "Unix domain sockets") and TCP-sockets. (libt2n::socket_client_connection, libt2n::socket_server_connection)

The client procedure stubs provide an interface to the server procedure implementations. To call the server procedure the client stub procedure is called. The client stub procedure transforms the procedure arguments and signature including the procedure "name" into a sequence of bytes using boost serialization [6]. This byte sequence represents a request to call a procedure with those arguments). Using the communication routines of libt2n the request is sent to the server. The server procedure stubs de-serialize the request and call the corresponding server procedure using the reconstructed arguments. The result of the server procedure is serialized and sent back to the client. Finally the result is de-serialized on client side again and returned to the caller.

The input for the code generator is standard C++ code [4] and you mark the procedures you want to expose to other processes. Because the interface is described in C++ directly there is no need for a interface description language (IDL, [5]). The code generator is used to create the client and server stubs for the marked procedures. The procedures can be grouped and each group maps to two classes (cmd_group_... and cmd_group_..._client). The cmd_group_..._client class provides the interface to call remote procedures. Each remote procedure maps to a method of this class and the constructor takes a connection object establishing the binding to the remote side. For each group the code generator is called and generates 6 output files: group_common.hxx, group_common.cpp, group_client.hxx, group_client.cpp, group_server.hxx, group_server.cpp. The _common files are used by client and server whereas the _client files contain the client stub code (the cmd_group_..._client class) and the _server files the server stub code.

To simplify the build process a Makefile snippet is provided that allows to create a server program and a client library (including a corresponding .pc file) using the autotools easily.

License

The libt2n libaray is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License version 2.1 as published by the Free Software Foundation. The code generator (libt2n-codegen) is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

Installation

Requirements

libt2n

• boost <http://www.boost.org/> (serialization <http://www.boost.org/libs/serialization/>)

libt2n-codegen

• gccxml <http://www.gccxml.org>
• libxmlpp <http://libxmlplusplus.sourceforge.net/>

client-wrapper

• boost <http://www.boost.org/> (bind <http://www.boost.org/libs/bind/>, function <http://www.boost.org/libs/function/>)
• gcc 4.1 or newer <http://gcc.gnu.org/>

Recommended

• pkg-config <http://pkgconfig.freedesktop.org/wiki/>
• autotools (autoconf <http://www.gnu.org/software/autoconf/>, automake, libtool)

Compilation

 ./configure && make check && make install
 

Usage

Take a look at the Usage example.

Homepage

The libt2n homepage with downloads and further information can be found at <http://www.intra2net.com/en/developer/libt2n/>.

References

• [1] inter-process communication (IPC), http://en.wikipedia.org/wiki/Inter-process_communication
• [2] remote procedure call (RPC), http://en.wikipedia.org/wiki/Remote_procedure_call and "THE RPC MODEL" http://www.faqs.org/rfcs/rfc1050.html
• [3] Figure: Remote procedure call overview, http://jan.newmarch.name/webservices/rpc_stub.png , Jan Newmarch "Web services" http://jan.newmarch.name/webservices/tutorial.html
• [4] in fact gccxml is used to parse the C++ code and the XML output of gccxml is used as input for the code generator
• [5] interface description language (IDL), http://en.wikipedia.org/wiki/Interface_description_language
• [6] boost serialization, http://www.boost.org/libs/serialization/